Klaipėdos universitetas

The article analyses the fishing and related occupations in the Curonian Lagoon region in the 19th – first half of the 20th centuries. A brief history of fishing in the Curonian Lagoon from ancient times is presented, thus providing historical context which might provide a better understanding of the processes that took place during the period analysed in the article. Available information from historical sources shows that besides fishing the lagoon fishermen were forced to engage in other occupations. The main reason for this was hard natural conditions of the region. Auxiliary fishing occupation soften were related to the fishermen’s skills acquired in fishing, such as boat building and management. Material of archaeological excavations carried out in 2012 at the site of former Kopgalis village is presented in the article. The material shows an important turning-point that took place in the 19 than 20th centuries in the region of the Curonian Lagoon – the transition from traditional fishing to a new activity – resort business. For the first time memoir material of Henrikas Cyrulis – native resident of Kintai village is presented in the study.

In this study, an NPZD model and a trophic network model that contains organism groups on the higher trophic levels were developed and linked using the “bottom-up control” approach. Such a linkage of models provides the possibility to use the advantages of both models; reproducing of the erratic behaviour of nutrients and plankton as realistic as possible, while still taking the more complex organisms in the trophic network, which respond to external forcing in a larger time scale. The models developed in this study were applied to the Curonian Lagoon that is an important estuarine ecosystem for Lithuania. The tests and simulations have proven that the results of the NPZD model were accurate enough for representing the nutrient and phytoplankton dynamics in the Curonian Lagoon as well as spatial differences which are of ecological interest. Linkage with trophic network model demonstrated NPZD model results to be consistent with the Curonian Lagoons ecosystem. The modelling results showed that primary production is relatively high in the Curonian Lagoon and is unlikely to be controlled by the organisms that are on the higher trophic levels of the food web. Analysis of the NPZD model scenarios with different nutrients inputs revealed that phosphorus is the main limiting nutrient for primary production in the Curonian Lagoon. However, different combinations of nitrogen and phosphorus inputs control the relative abundance of different phytoplankton groups. Investigation of reaction of ecosystem to water temperature increase showed that the temperature increase finally leads to decrease of available phytoplankton to upper levels of the food web.